Sx195 power loss

[—Яiвs>]

@ScottS Thanks for your message!
Planning on changing my plugs this weekend. I have the round plug gapper. So even though it's not super accurate I'll make sure all four plugs have about the same gap.
Where would you apply silicone in the intake? I've just changed my air filter. What do you call tunnel?

I believe he’s referring to sealing all the crevices in front of the impeller also referred to as the tunnel/intake for the jet pump. Smoothing this section decreases cavitation.

 

[ScottS]

@sebmcadet

Regarding sealing the intake tunnel, check out this thread by @2kwik4u

https://jetboaters.net/threads/hero-or-zero-resealed-my-jet-pump.17845/

When you have a minute, read through the posts on the FAQ section. Super informative for anyone new to jet boats or wanting to learn more.

 

[sebmcadet]

Thanks for your response guys.
I did read your long thread, and it sounds like I've got plenty of room for further improvement.
However, here is where I stand:

1. A month ago my engine would go above 7000rpm. Now it often settles around 6600rpm
2. After running at WOT for 30-40min my pisser temp is hot but not scalding. I don't suspect heat soak but I can't be 100% sure.
3. I've removed a little bit of oil, changed the plugs, tightened the throttle cable this weekend.
Right out the gate (cold engine, water temp 82-83F) I almost hit 7000rpm (more like 6900).
When tubing I would hit 6600.
After an hour it would not go over 6600rpm -- Unless turning right (leaning on starboard side) and I would gain 200rpm! => Could this be a injection issue?? (Injection is on the starboard side)

I don't feel it runs terribly wrong, it's just frustrating that it doesn't seem to run perfectly (it's > 5yrs old, but only has 170hrs!!!)

Let me know your thoughts.

 

[ScottS]

@sebmcadet I am not an expert by any means. Take this with a grain of salt.

1 & 2 - I attribute to warm weather and warm water. I'll bet in the next month or two as temps start to fall you see your RPM's rise back up. After an hour or so, your engine is up to temp, depending on load and use you may be getting the temperatures into the performance limited mode. There is no warning sent to the dash when it enters this limited mode that I am aware of and usually running the engine at no-wake speeds for a little bit can cool the engine and help you regain performance. But with water in the 80's and Air temps likely above that, it doesn't surprise me that you are hovering in the 6000's.

3 - Less confident on this, but I wonder if when you are turning right you are loading the pump differently and it is able to pull water with less turbulence. This may be related to the need to check the sealing of the intake tunnel. If one side of the tunnel has a better seal than the other, perhaps when the pump loads differently the water is flowing with more or less turbulence.

 

[—Яiвs>]

@sebmcadet I am not an expert by any means. Take this with a grain of salt.

1 & 2 - I attribute to warm weather and warm water. I'll bet in the next month or two as temps start to fall you see your RPM's rise back up. After an hour or so, your engine is up to temp, depending on load and use you may be getting the temperatures into the performance limited mode. There is no warning sent to the dash when it enters this limited mode that I am aware of and usually running the engine at no-wake speeds for a little bit can cool the engine and help you regain performance. But with water in the 80's and Air temps likely above that, it doesn't surprise me that you are hovering in the 6000's.

3 - Less confident on this, but I wonder if when you are turning right you are loading the pump differently and it is able to pull water with less turbulence. This may be related to the need to check the sealing of the intake tunnel. If one side of the tunnel has a better seal than the other, perhaps when the pump loads differently the water is flowing with more or less turbulence.

He might be into something here, perhaps a short jog in no wake to clear out some heat and a retest would yield some kind of result. I did find a cooling upgrade kit for our SVHO and a thermostat delete on GreenHulk seems with any performance mod you want to keep cool. If we are surfing, boarding or running WOT across the lake still generating a descent amount of heat with water temps in the 80s might just need a breather.

 

[sebmcadet]

Thanks @ScottS and @—Яiвs> for your replies.
I think I'm feeling a bit better about the whole power loss thing. It did happen the first time during a very warm weekend at sea with water temperature as high as it can get at the end of the summer.
I had found plenty of posts from 1-2 years ago about the SHVO upgrade for $200-$300. These parts are now 10x more expensive. So that will have to wait.
I'll look into the intake tunnel and see what can be improved next.
And lastly I will keep in mind to run the engine at no-wake speed more often

 

[ScottS]

@sebmcadet You are in an SX195 correct? The 195's are already an SVHO, so I am curious about which upgrade you are considering.

 

[sebmcadet]

No, AR192. I have an SHO IC.

 

[ScottS]

No, AR192. I have an SHO IC.

My bad, I got you confused with the original poster of the thread.